Tetrametallic hydrocarbon conversion catalyst and uses thereof

ABSTRACT

A CATALYTIC COMPOSITE COMPRISING A COMBINATION OF CATALYTICALLY EFFECTIVE AMOUNTS OF A PLATINUM OR PALLADIUM COMPONENT, AN IRIDIUM COMPONENT, A RHENIUM COMPONENT AND A TIN COMPONENT WITH A POROUS CARRIER MATERIAL IS DISCLOSED. THE PRIMCIPAL UTILITY OF THIS COMPOSITE IS IN THE CONVERSION OF HYDROCARBONS, PARTICULARLY IN THE REFORMING OF A GASOLINE FRACTION. A SPECIFIC EXAMPLE OF THE DISCLOSED CATALYTIC COMPOSITE IS A COMBINATION OF A PLATINUM COMPONENT, AN IRIDIUM COMPONENT, A RHENIUM COMPONENT, A TIN COMPONENT, AND A HALOGEN COMPONENT WITH AN ALUMINA CARRIER MATERIAL IN AMOUNTS SUFFICIENTLY TO RESULT IN A COMPOSITE CONTAINING, ON AN ELEMENTAL BASIS, ABOUT :.0.01 TO 2 WT. PERCENT PLATINUM, ABOUT 0.01 TO ABOUT 2 WT. PERCENT IRIDIUM, ABOUT 0.01 TO 2 WT. PERCENT RHENIUM, ABOUT 0.01 TO 5 WT. PERCENT TIN AND ABOUT 0.1 TO 3.5 WT. PERCENT HALOGEN.

United States Patent TETRAMETALLIC HYDROCARBON CONVERSION CATALYST ANDUSES THEREOF Richard E. Rausch, Mundelein, Ill., assignor to UniversalOil Products Company, Des Plaines, Ill.

No Drawing. Continuation-impart of application Ser. No. 142,079, May 10,1971, now Patent No. 3,702,294, which is a continuation-impart ofapplications Ser. No. 819,114, Apr. 24, 1969, now abandoned, and Ser.No. 807,910, Mar. 17, 1969, now Patent No. 3,740,328. This applicationNov. 6, 1972, Ser. No. 304,177

Int. Cl. B01j 11/12; C10g 35/08 U.S. Cl. 208-139 23 Claims ABSTRACT OFTHE DISCLOSURE A catalytic composite comprising a combination ofcatalytically effective amounts of a platinum or palladium component, aniridium component, a rhenium component and a tin component with a porouscarrier material is disclosed. The principal utility of this compositeis in the conversion of hydrocarbons, particularly in the reforming of agasoline fraction. A specific example of the disclosed catalyticcomposite is a combination of a platinum component, an iridiumcomponent, a rhenium component, a tin component, and a halogen componentwith an alurnina carrier material in amounts sufficiently to result in acomposite containing, on an elemental basis, about 0.01 to 2 wt. percentplatinum, about 0.01 to about 2 wt. percent iridium, about 0.01 to 2 wt.percent rhenium, about 0.01 to 5 wt. percent tin and about 0.1 to 3.5wt. percent halogen.

CROSS-REFERENCE TO RELATED APPLICATIONS This application is acontinuation-in-part of my prior, copending application Ser. No. 142,079which was filed on May 10, 1971, now Pat. No. 3,702,294, and which is inturn a continuation-in-p-art of (1) my prior, now abandoned applicationSer. No. 819,114 which was filed on Apr. 24, 1969- and (2) my prior,copending application Ser. No. 807,910 which was filed on Mar. 17, 1969,now U.S. Pat. 3,740,328.

DISCLOSURE The subject of the present invention is a novel tetrametalliccatalytic composite which has exceptional activity and resistance todeactivation when employed in a hydrocarbon conversion process thatrequires a catalyst having both a hydrogenation-dehydrogenation functionand a cracking function. More precisely, the present invention involvesa novel dual-function catalytic composite which, quite surprisingly,enables substantial improvements in hydrocarbon conversion processesthat have traditionally used a dual-function catalyst. In anotheraspect, the present invention comprehends the improved processes thatare produced by the use of a catalytic composite comprsing a combinationof catalytically effective amounts of a platinum or palladium component,an iridium component, a rhenium component, and a tin component with aporous carrier material; specifically, an improved reforming processwhich utilizes the subject catalyst to sharply improve the performancecharacteristics of the overall process.

Composites having a hydrogenation-dehydrogenation function and acracking function are widely used today as catalysts in many industries,such as the petroleum and petrochemical industry, to accelerate a widespectrum of hydrocarbon conversion reactions. Generally, the crackingfunction is thought to be associated with an acidacting material of theporous, adsorptive, refractory oxide type which is typically utilized asthe support or carrier for 3,790,473 Patented Feb. 5, 1974 Ice a heavymetal component such as the metals or compounds of metals of Groups Vthrough VIII of the Periodic Table to which are generally attributed thehydrogenation-dehydrogenation function.

These catalytic composites are used to accelerate a wide variety ofhydrocarbon conversion reactions such as hydrocracking, isomerization,dehydrogenation, hydrogenation, desulfurization, cyclization,alkylation, polymerization, cracking, hydroisomerization, etc. In manycases, the commercial applications of these catalysts is in processeswhere more than one of these reactions are proceeding simultaneously. Anexample of this type of process is reforming wherein a hydrocarbon feedstream containing paraflins and naphthenes is subjected to conditionswhich promote dehydrogenation of naphthenes to aromatics,dehydr'ocyclization of parafiins to aromatics, isomerization ofparaffins and naphthenes, hydrocracking of naphthenes and paraflins andthe like reactions, to produce a high octane, aromatic-rich productstream. Another example is a hydrocracking process wherein catalysts ofthis type are utilized to eifect selective hydrogenation and cracking ofhigh molecular weight unsaturated materials, selective hydrocracking ofhigh molecular weight materials, and other like reactions, to produce agenerally lower boiling, more valuable output stream. Yet anotherexample is an isomerization process wherein a hydrocarbon fraction whichis relatively rich in straight-chain parafiin compounds is contactedwith a dual-function catalyst to produce an outpt stream rich inisoparaffin compounds.

Regardless of the reaction involved or the particular process involved,it is of critical importance that the dualfunction catalyst exhibit notonly the capability to intially perform its specified functions, butalso that it has the capability to perform them satisfactorily forprolonged periods of time. The analytical terms used in the art tomeasure how well a particular catalyst performs its intended functionsin a particular hydrocarbon reaction environment are activity,selectivity, and stability. And for purposes of discussion here, theseterms are conveniently defined for a given charge stock as follows: (1)activity is a measure of the catalysts ability to convert hydrocarbonreactants into products at a specified severity level where severitylevel means the conditions used-that is, the temperature, pressure,contact time, and presence of diluents such as H (2) selectivity refersto the weight or volume or mole percent of the reactants that areconverted into the desired product and/ or products relative to theamount charged or converted; (3) stability refers to the rate of changewith time of the activity and selectivity parameters-obviously, thesmaller rate implying the more stable catalyst. In a reforming process,for example, activity commonly refers to the amount of conversion thattakes place for a given charge stock at a specified severity level andis typically measured by octane number of the C product stream;selectivity refers to the amount of 0 yield that is obtained at theparticular activity level relative to the amount of the charge stock;and stability is typically equated to the rate of change with time ofactivity, as measured by octane number of C product, and of selectivity,as measured by C yield. Actually, the last statement is not strictlycorrect because generally a continuous reforming process is rim toproduce a constant octane C product with severity level beingcontinuously adjusted to attain this result; and, furthermore, theseverity level is for this process usually varied by adjusting theconversion temperature in the reaction zone so that, in point of fact,the rate of change of activity finds response in the rate of change ofconversion temperatures and changes in this last parameter arecustomarily taken as indicative of activity stability.

As is Well known to those skilled in the art, the principal cause ofobserved deactivation or instability of a dualfunction catalyst when itis used in a hydrocarbon conversion reaction is associated with the factthat coke forms on the surface of the catalyst during the course of thereaction. More specifically, in these hydrocarbon conversion processes,the conditions utilized typically result in the formation of heavy, highmolecular weight, black, solid or semi-solid, carbonaceous materialwhich coats the surface of the catalyst and reduces its activity byshielding its active sites from the reactants. In other words, theperformance of this dual-function catalyst is sensitive to the presenceof carbonaceous deposits on the surface of the catalyst. Accordingly,the major problem facing workers in this area of the art is thedevelopment of more active and selective catalytic composites that arenot as sensitive to the presence of these carbonaceous materials and/orhave the capability to suppress the rate of the formation of thesecarbonaceous materials on the catalyst. Viewed in terms of performanceparameters, the problem is to develop a dual-function catalyst havingsuperior activity, selectivity, and stability characteristics. Inparticular, for a reforming process the problem is typically expressedin terms of shifting and stabilizing the C yield-octane relationship-(2yield being representative of selectivity and octane being proportionalto activity.

I have now found a dual-function tetrametallic catalytic composite whichpossesses improved activity, selectivity, and stability characteristicswhen it is employed in a process for the conversion of hydrocarbons ofthe type which have heretofore utilized dual-function catalyticcomposites such as processes for isomerization, hydroisomerization,dehydrogenation, desulfurization, denitrogenization, hydrogenation,alkylation, delkylation, hydrodealkylation, transalkylation,cyclization, dehydrocyclization, cracking, hydrocracking, reforming, andthe like processes. In particular, I have ascertained that the use of atetrametallic catalyst, comprising a combination of catalyticallyeffective amounts of a platinum or palladium component, an iridiumcomponent, a rhenium component, and a tin component with a porousrefractory carrier material, can enable the performance of hydrocarbonconversion processes which have traditionally utilized dualfunctioncatalysts to be substantially improved. Moreover, I have determined thata tetrametallic catalytic composite, comprising a combination ofcatalytically effective amounts of a platinum component, an iridiumcomponent, a tin component, a rhenium component, and a halogen componentwith an alumina carrier material, can be utilized to substantiallyimprove the performance of a reforming process which operates on agasoline fraction to produce a high-octane reformate. In the case of areforming process, the principal advantage associated with the use ofthe novel catalyst of the present invention involves the acquisition ofthe capability to operate in a stable manner in a high severityoperation; for example, a low pressure reforming process designed toproduce a reformate having an octane of about 100 F-1 clear. Asindicated, the present invention essentially involves the finding thatthe addition of a tin, iridium and rhenium component to a dual-functionhydrocarbon conversion catalyst containing a platinum group componentenables the performance characteristics of the catalyst to be sharplyand materially improved particularly in the areas of increased hydrogenand aromatic production, temperature and yield stability and activity.

It is accordingly, one object of the present invention to provide atetrametallic hydrocarbon conversion catalyst having superiorperformance characteristics when utilized in a hydrocarbon conversionprocess. A second object is to provide a catalyst having dual-functionhydrocarbon conversion performance characteristics that are relativelyinsensitive to the deposition of hydrocarbonaceous material thereon. Athird object, is to provide preferred methods of preparation of thiscatalytic composite which insures the achievement and maintenance of 1tsproperties. Another object is to provide an improved reforming catalysthaving superior activity, selectivity, and stability characteristics.Yet another object is to provide a dual-function hydrocarbon conversioncatalyst which utilizes a combination of relatively inexpensivecomponent, tin, and relatively expensive components, iridium andrhenium, to promote a platinum metal component.

In brief summary, the present invention is, in one embodiment, acatalytic composite comprising a combination of a platinum or palladiumcomponent, an iridium component, a rhenium component, and a tincomponent with a porous carrier material. The porous carrier material istypically a porous, refractory material such as a refractory inorganicoxide, and the iridium component, the tin component, the rheniumcomponent, and the platinum or palladium component are usually utilizedin relatively small amounts which are effective to catalytically promotethe desired hydrocarbon conversion reaction. Moreover, substantially allof the platinum or palladium, iridium and rhenium components of thecatalyst are present therein in the elemental metallic state, andsubstantially all of the tin component is present therein in anoxidation state above that of the elemental metal.

A second embodiment relates to a catalytic composite comprising acombination of a platinum component, an iridium component, a rheniumcomponent, a tin component, and a halogen component with an aluminacarricr material. These components are preferably present in thecomposite in amounts sufiicient to result in the final compositecontaining, on an elemental basis, about .1 to about 3.5 wt. percenthalogen, about 0.01 to about 2 wt. percent platinum, about 0.01 to about2 wt. percent iridium, about 0.01 to about 2 wt. percent rhenium, andabout 0.01 to about 5 wt. percent tin. In addition, the tin component isuniformly distributed throughout the carrier material and substantiallyall of the tin component is present therein in an oxidation state abovethat of the elemental metal. In contrast, substantially all of theplatinum, iridium and rhenium components are present in the composite inthe elemental metallic state.

Another embodiment relates to a catalytic composite comprising acombination of the catalytic composite characterized in the secondembodiment with a sulfur component in an amount sufficient toincorporate about 0.05 to about 0.5 wt. percent sulfur, calculated on anelemental basis.

Yet another embodiment relates to a process for the conversion ofhydrocarbon comprising contacting the hydrocarbon and hydrogen with thecatalytic composite of the first embodiment at hydrocarbon conversionconditions.

A preferred embodiment relates to a process for reforming a gasolinefraction which comprises contacting the gasoline fraction and hydrogenwith the catalytic composite described above in the second embodiment atreforming conditions selected to produce a high-octane reformate.

Other objects and embodiments of the present invention relates toadditional details regarding preferred catalytic ingredients, amounts ofingredients, suitable methods of composite preparation, operatingconditions for use in the hydrocarbon conversion processes, and the likeparticulars. They are hereinafter given in the following detaileddiscussion of each of these facets of the present invention.

The tetrametallic catalyst of the present invention comprises a porouscarrier material or support having combined therewith catalyticallyeffective amounts of a platinum or palladium component, an iridiumcomponent, a rhenium component, a tin component, and in the preferredcase, a halogen component. Considering first the porous carrier materialutilized in the present invention, it is preferred that the material bea porous, adsorptive,

high-surface area support having a surface area of about 25 to about 500m. g. The porous carrier material should be relatively refractory to theconditions utilized in the hydrocarbon conversion process, and it isintended to include within the scope of the present invention carriermaterials which have traditionally been utilized in dualfunctionhydrocarbon conversion catalysts such as: 1) activated carbon, coke, orcharcoal; (2) silica or silica gel, silicon carbide, clays, andsilicates including those synthetically prepared andnaturally-occurring, which may or may not be acid treated, for example,attapulgus clay, china clay, diatomaceous earth, fullers earth, kaoline,kieselguhr, etc.; (3) ceramics, porcelain, crushed firebrick, bauxite;(4) refractory inorganic oxides such as alumina, titanium dioxide,zirconium dioxide, chromium oxide, zinc oxide, magnesia, thoria, boria,silica-alumina, silica-magnesia, chromia-alumina, alumina-boria,silica-zirconia, etc. (5) crystalline zeolitic aluminosilicates such asnaturallyoccuring or synthetically-prepared mordenite and/or faujasite,either in the hydrogen form or in a form which has been treated withmulti-valent cations; (6) spinels Such as MgA1 O FCA1204, RHA1204,MI1A1204, CaAl O and other like compounds having the formula Mo-Al Owhere M is a metal having a valence of 2; and (7) combinations ofelements from one or more of these groups. The preferred porous carriermaterials for use in the present invention are refractory inoragnicoxides, with best results obtained with an alumina carrier material.Suitable alumina materials are the crystalline aluminas known as thegamma-, eta-, and theta-alumina, with gammaor eta-alumina giving bestresults. In addition, in some embodiments the alumina carrier materialmay contain minor proportions of other well-known refractory inorganicoxides such as silica, zirconia, magnesia, etc.; however, the preferredsupport is substantially pure gammaor etaalumina. Preferred carriermaterials have an apparent bulk density of about 0.3 to about 0.7 g./cc.and surface area characteristics such that the average pore diameter isabout 20 to 300 angstroms, the pore volume is about 0.1 to about 1ml./g. and the surface area is about 100 to about 500 m.*/ g. ingeneral, best results are typically obtained with a gamma-aluminacarrier material which is used in the form of spherical particleshaving: a relatively small diameter (i.e. typically about inch), anapparent bulk density of about 0.5 to about 0.6 g./cc., a pore volume ofabout 0.4 ml./g., and a surface area of about 175 m. /g.

The preferred alumina carrier material may be prepared in any suitablemanner and may be synthetically prepared or natural occurring. Whatevertype of alumina is employed it may be activated prior to use by one ormore treatments including drying, calcination, steaming, etc., and itmay be in a form known as activated alumina, activated alumina ofcommerce, porous alumina, alumina gel, etc. For example, the aluminacarrier may be prepared by adding a suitable alkaline reagent, such asammonium hydroxide to a salt of aluminum such as aluminum chloride,aluminum nitrate, etc., in an amount to form an aluminum hydroxide gelwhich upon drying and calcining is converted to alumina. The aluminacarrier may be formed in any desired shape such as spheres, pills,cakes, extrudates, powders, granules, etc., and utilized in any desiredsize. For the purpose of the present invention a particularly preferredform of alumina is the sphere; and alumina spheres may be continuouslymanufactured by the well-known oil drop method which comprises: formingan alumina hydrosol by any of the techniques taught in the art andpreferably by reacting aluminum metal with hydrochloric acid, combiningthe resulting hydrosol with a suitable gelling agent and dropping theresultant mixture into an oil bath maintained at elevated temperatures.The droplets of the mixture remain in the oil bath until they set andform hydrogel spheres. The spheres are then continuously withdrawn fromthe oil bath and typically subjected to specific aging treatments in oiland an ammoniacal solution to further improve their physicalcharacteristics. The resulting aged and gelled particles are then washedand dried at a relatively low temperature of about 300 F. to about 400F. and subjected to a calcination procedure at a temperature of about850 F. to about 1300 F. for a period of about 1 to about 20 hours. Thistreatment effects conversion of the alumina hydrogel to thecorresponding crystalline gamma-alumina. See the teachings of US. Pat.No. 2,620,314 for additional details.

One essential constituent of the catalyst of the present invention is atin component. It is an essential feature of the present invention thatthe tin component is present in the composite in an oxidation stateabove that of the elemental metal. That is, the tin component will existin the present catalytic composite in either the +2 or +4 oxidationstate with the latter being the most likely state. Accordingly, the tincomponent will be present in the composite as a chemical compound, suchas the oxide, sulfide, halide, etc., wherein tin is in the requiredoxidation state, or as a chemical combination with the carrier materialin which combination the tin exists in this higher oxidation state. Onthe basis of the evidence currently available, it is believed that thetin component in the subject composite exists as stannic or stannousoxide. It is important to note that this limitation on the state of thetin component requires extreme care in the preparation and use of thesubject composite in order to insure that it is subjected to oxidationconditions effective to produce tin oxide and that it is not thereaftersubjected to high temperature reduction conditions effective to producethe tin metal. Preferably, the tin component is used in an amountsufficient to result in the final catalytic composite cotaining, on anelemental basis, about 0.01 to about 5 wt. percent tin, with bestresults typically obtained with about 0.1 to about 2 wt. percent tin.

This tin component may be incorporated inthe catalytic composite in anysuitable manner such as by coprecipitation or cogellation with theporous carrier material, ion exchange with the carrier material orimpregnation of the carrier material at any stage in the preparation. Itis to be noted that it is intended to include with in the scope of thepresent invention all conventional methods for incorporating a metalliccomponent in a catalytic composite, and the particular method ofincorporation used is not deemed to be an essential feature of thepresent invention. One preferred method of incorporating the tincomponent in the catalytic composite involves coprecipitating the tincomponent during the preparation of the preferred refractory oxidecarrier material. In the preferred case, this involves the addition ofsuitable soluble tin compounds such as stannous or stannic halide to thealumina hydrosol, and then combining the hydrosol with a suitablegelling agent, and dropping the resulting mixture into an oil bath,etc., as explained in detail hereinbefore. Followmg the calcinationstep, there is obtained a carrier mate rial comprising an intimatecombination of alumina and stannic oxide. Another preferred method ofincorporating the tin component into the catalyst composite involves theutilization of a soluble, decomposable compound of tin to impregnate theporous carrier material. Thus, the tin component may be added to thecarrier material by commmgling the latter with an aqueous solution of asuitable tin salt or water-soluble compound of tin such as stannousbromide, stannous chloride, stannic chloride, stanic chloridepentahydrate, stannic chloride tetrahydrate, stannic chloridetrihydrate, stannic chloride diamine, stannic trichloride bromide,stannic chromate, stannous fluoride, stannic fluoride, stannic iodide,stannic sulfate, stannic tartrate, and the like compounds. Theutilization of a tin chloride compound, such as stannous or stannicchloride is particularly preferred since it facilitates theincorporation of both the tin component and at least a minor amount ofthe preferred halogen component in a single step. In general, the tincomponent can be impregnated either prior to, simultaneously with, orafter the other metallic components are added to the carrier material.However, I have found that excellent results are obtained when the tincomponent is impregnated simultaneously with the other metalliccomponents. In fact, a preferred impregnation solution containschloroplatinic acid, perrhenic acid, chloroiridic acid, hydrogenchloride, and stannous or stannic chloride.-

Regardless of which tin compound is used in the preferred impregnationstep, it is extremely important that the tin component be uniformlydistributed throughout the carrier material during this step. In orderto achieve this objective it is necessary to maintain the pH of theimpregnation solution in at a relatively low level a range of about 1 toabout 7, preferably 1 to about 3, and to dilute the impregnationsolution to a volume which is approximately equivalent to or greaterthan the volume of the carrier material which is impregnated. It ispreferred to use a volume ratio of impregnation solution to carriermaterial of at least :1 and preferably about 0.75:1 to about 2:1 ormore. Similarly, it is preferred to use a relatively long contact timeduring the impregnation step ranging from about A hour up to about /2hour or more before drying to remove excess solvent in order to insure ahigh dispersion of the tin component into the carrier material. Thecarrier material, is, likewise, preferably constantly agitated duringthis preferred impregnation step.

A second essential ingredient of the subject catalyst is the platinum orpalladium component. That is, it is intended to cover the use ofplatinum or palladium or mixtures thereof as a second component of thepresent composite. It is an essential feature of the present inventionthat substantially all of this platinum or palladium component existswithin the final catalytic composite in the elemental metallic state.Generally, the amount. of this component present in the final catalystcomposite is small compared to the quantities of the other componentscombined therewith. In fact, the platinum or palladium componentgenerally will comprise about 0.01 to about 2 wt. percent of the finalcatalytic composite, calculated on an elemental basis. Excellent resultsare obtained when the catalyst contains about 0.05 to about 1 wt.percent of platinum or palladium metal.

This platinum or palladium component may be incorporated in thecatalytic composite in any suitable manner known to result in arelatively uniform distribution of this component in the carriermaterial such as coprecipitation or cogellation, ion-exchange, orimpregnation. [he preferred method of preparing the catalyst involvesthe utilization of a soluble, decomposable compound of platinum orpalladium to impregnate the carrier material in a relatively uniformmanner. For example, this component may be added to the support bycommingling the latter with an aqueous solution of chloroplatinic orchloropalladic acid. Other water-soluble compounds of platinum orpalladium may be employed in impregnation solutions and include ammoniumchloroplatinate, bromoplatinic acid, platinum dichloride, platinumtetrachloride hydrate, platinum dichlorocarbonyl dichloride,dim'trodiaminoplatinum, palladium chloride, palladium nitrate, palladiumsulfate, etc. The utilization of a platinum or palladium chloridecompound, such as chloroplatinic or chloropalladic acid, is preferredsince it facilitates the incorporation of both the platinum or palladiumcomponent and at least a minor quantity of the preferred halogencomponent in a single step. Hydrogen chloride or the like acid is alsogenerally added to the impregnation solution in order to furtherfacilitate the incorporation of the halogen component and the uniformdistribution of the metallic component throughout the carrier material.In addition, it is generally preferred to impregnate the carriermaterial after it has been calcined in order to minimize the risk ofwashing away the valuable platinum or palladium compounds; however, insome cases it may be advantageous to impregnate the carrier materialwhen it is in a gelled state.

Yet another essential ingredient of the present catalytic composite isan iridium component. It is of fundamental importance that substantiallyall of the iridium component exists within the catalytic composite ofthe present invention in the elemental state and the subsequentlydescribed reduction procedure is designed to accomplish this objective.The iridium component may be utilized in the composite in any amountwhich is catalytically eifective, with the preferred amount being about0.01 to about 2 wt. percent thereof, calculated on an elemental iridiumbasis. Typically bests results are obtained with about 0.05 to about 1wt. percent iridium. It is, additionally, preferred to select thespecific amount of iridium from within this broad weight range as afunction of the amount of the platinum or palladium component, on anatomic basis, as is explained hereinafter.

This iridium component may be incorporated into the catalytic compositein any suitable manner known to those skilled in the catalystformulation art which results in a relatively uniform dispersion ofiridium in the carrier material. In addition, it may be added at anystage of the preparation of the composite-either during preparation ofthe carrier material or thereafterand the precise method ofincorporation used is not deemed to be critical. However, best resultsare thought to be obtained when the iridium component is relativelyuniformly distributed throughout the carrier material, and the preferredprocedures are the ones known to result in a composite having thisrelatively uniform distribution. One acceptable procedure forincorporating this component into the composite involves cogelling orcoprecipitating the iridium component during the preparation of thepreferred carrier material, alumina. This procedure usually comprehendsthe addition of a soluble, decomposable compound of iridium such asiridium tetrachloride to the alumina hydrosol before it is gelled. Theresulting mixture is then finished by conventional gelling, aging,drying and calcination steps as explained hereinbefore. A preferred wayof incorporating this component is an impregnation step wherein theporous carrier material is impregnated with a suitableiridium-containing solution either before, during or after the carriermaterial is calcined. Preferred impregnation solutions are aqueoussolutions of water soluble, decomposable iridium compounds such asiridium tribromide, iridium dichloride, aridium tetrachloride, iridiumoxaltic acid, iridium sulfate, potassum iridochloride, chloroiridic acidand the like compounds. Best results are ordinarily obtained when theimpregnation solution is an aqueous solution of chloroiridic acid orsodium chloroiridate. This component can be added to the carriermaterial, either prior to, simultaneously with or after the othermetallic components are combined therewith. Best results are usuallyachieved when this component is added simultaneously with the othermetallic components. In fact, excellent results are obtained, asreported in the examples, with a one step impregnation procedure usingan aqueous solution comprising chloroplatinic or chloropalladic acid,chloroiridic acid, hydrochloric acid and perrhenic acid.

Yet another assential component of the catalyst of the present inventionis the rhenium component. It is an essential feature of the presentinvention that substantially all of the rhenium component of thecatalyst is present therein as the elemental metal, and the hereinafterdescribed reduction step is specifically designed to reduce thiscomponent along with the platinum or palladium component and the iridiumcomponent. The rhenium component is preferably utilized in an amountsufficient to result in a final catalytic composite containing about0.01 to about 2 wt. percent rhenium and preferably about 0.05 to about1, calculated on an elemental basis.

The rhenium component may be incorporated in the catalytic composite inany suitable manner and at any stage in the preparation of the catalyst.It is generally advisable to incorporate the rhenium component in animpregnation step after the porous carrier material has been formed inorder that the expensive metal will not be lost due to washing andpurification treatments which may be applied to the carrier materialduring the course of its production. Although any suitable method forincorporating a catalytic component in a porous carrier material can beutilized to incorporate the rehenium component, the preferred procedureinvolves impregnation of the porous carrier material. The impregnationsolution can, in general, be a solution of a suitable soluble,decomposable rhenium salt such as ammonium perrhenate, sodiumperrhenate, potassium perrhenate, and the like salts. In addition,solutions of rhenium halides such as rhenium chloride may be used; thepreferred impregnation solution is, however, an aqueous solution ofperrhenic acid. The porous carrier material can be impregnated with therhenium component either prior to, simultaneously with, or after theother components mentioned herein are combined therewith. Best resultsare ordinarily achieved when the rhenium component is impregnatedsimultaneously with the platinum or pallidium, tin and iridiumcomponents. In fact, excellent results are obtained with a one stepimpregnation procedure utilizing as an impregnation solution, an aqueoussolution of chloroplatinic acid, chloroiridic acid, perrhenic acid,stannic chloride, and hydrochloric acid.

It is generally preferred to incorporate a halogen component into thetetrametallic catalytic composite of the present invention. Accordingly,a preferred embodiment of the present invention involves a catalyticcomposite comprising a combination of a platinum or palladium component,an iridium component, a tin component, a rhenium component, and ahalogen component with an alumina carrier material. Although the preciseform of the chemistry of the association of the halogen component withthe carrier material is not entirely known, it is customary in the artto refer to the halogen component as being combined with the carriermaterial, or with the other ingredients of the catalyst in the form ofthe halide (e.g. as the chloride). This combined halogen may be eitherfluorine, chlorine, iodine, bromine, or mixtures thereof. Of these,fluorine and, particularly, chlorine are preferred for the purposes ofthe present invention. The halogen may be added to the carrier materialin any suitable manner, either during preparation of the support orbefore or after the addition of the other components. For example, thehalogen may be added, at any stage of the preparation of the carriermaterial or to the calcined carrier material, as an aqeuous solution ofa suitable, decomposable halogen containing compound such as hydrogenfluoride, hydrogen chloride, hydrogen bromide, ammonium chloride, etc.The halogen component or a portion thereof, may be combined with thecarrier material during the impregnation of the latter with the platinumor pallidium or iridium components; for example, through the utilizationof a mixture of chloroplatinic acid and hydrogen chloride. In anothersituation, the alumina hydrosol which is typically utilized to form thepreferred alumina carrier material may contain halogen and thuscontribute at least a portion of the halogen component to the finalcomposite. For reforming, the halogen will be typically combined withthe carrier material in an amount suflicient to result in a finalcomposite that contains about 0.1 to about 3.5%, and preferably about0.5 to about 1.5% by weight of halogen calculated on an elemental basis.In isomerization or hydrocracking embodiments, it is generally preferredto utilize relatively larger amounts of halogen in thecatalysttypically, ranging up to about 10 wt. percent halogen calculatedon an elemental basis, and more preferably about 1 to about 5 wt.percent.

Regarding the preferred amounts of the various metallic components ofthe subject catalyst, I have found it to be a good practice to specifythe amounts of the iridium component, the rhenium component, and the tincomponent as a function of the amount of the platinum or palladiumcomponent. On this basis, the amount of the rhenium components isordinarily selected so that the atomic ratio of rhenium to platinum orpallidium metal contained in the composite is about 0.1:1 to about 3:1,with the preferred range being about 0.25 :1 to about 1.5 :1 Similarly,the amount of the tin component is ordinarily selected to produce acomposite containing an atomic ratio of tin to platinum or palladiummetal of about 0.1:1 to about 3:1, with the preferred range bing about0.25:1 to about 2:1. In the same manner, the amount of the iridiumcomponent is preferably selected so that the atomic ratio of iridium toplatinum or pallidium is about 0.1:1 to about 2:1.

Another significant parameter for the instant catalyst is the totalmetals content which is defined to be the sum of the platinum orpallidium component, the iridium component, the rhenium component, andthe tin component, calculated on an elemental tin, rhenium, iridium andplatinum or pallidium metal basis. Good results are ordinarily obtainedwith the subject catalyst when this parameter is fixed at a value ofabout 0.15 to about 5 wt. percent, with best results ordinarily achievedat a metals loading of about 0.3 to about 2 wt. percent.

Integrating the above discussion of each of the essen tial and preferredcomponents of the catalytic composite, it is evident that a particularlypreferred catalytic composite comprises a combination of a platinumcomponent, an iridium component, a rhenium component, a tin component,and a halogen component with an alumina carrier material in amountssufficient to result in the composite containing about 0.5 to about 1.5wt. percent halogen, about 0.05 to about 1 wt. percent platinum, about0.05 to about 1 wt. percent iridium, about 0.05 to about 1 wt. percentrhenium, and about 0.05 to about 2 wt. percent tin. Accordingly,specific examples of especially preferred catalytic composites are asfollows: (1) a catalytic composite comprising a combination of 0.5 wt.percent tin, 0.5 wt. percent rhenium, 0.5 wt. percent iridium, 0.75 wt.percent platinum, and about 0.5 to about 1.5 wt. percent halogen with analumina carrier material; (2) a catalytic composite comprising acombination of 0.1.wt. percent tin, 0.1 wt. percent rhenium, 0.1 wt.percent iridium, 0.1 wt. percent platinum, and about 0.5 to about 1.5wt. percent halogen with an alumina carrier material; (3) a catalyticcomposite comprising a combination of about 0.375 wt. percent tin, 0.375wt. percent rhenium, 0.375 Wt. percent platinum, 0.375 wt. percentiridium and about 0.5 to about 1.5 wt. percent halogen with an aluminacarrier material; (4) a catalytic composite comprising a combination of0.12 wt. percent tin, 0.1 wt. percent rhenium, 0.2 wt. percent platinum,0.2 wt. percent iridium and about 0.5 to about 1.5 wt. percent halogenwith an alumina carrier material; (5) a catalytic composite comprising acombination of 0.25 wt. percent tin, 0.25 wt. percent platinum, 0.25 wt.percent iridium, 0.25 wt. percent rhenium, and about 0.5 to about 1.5wt. percent halogen with an alumina carrier material; and, (6) acatalytic composite comprising a combination of 0.2 wt. percent tin, 0.2wt. percent rheniurn, 0.2 wt. percent platinum, 0.2 wt. percent iridiumand about 0.5 to about 1.5 wt. percent halogen with an alumina carriermaterial. The amounts of the components reported in these examples are,of course, calculated on an elemental basis.

In embodiments of the present invention wherein the instanttetrametallic catalytic composite is used for dehydrogenation ofdehydrogenatable hydrocarbons or for the hydrogenation of hydrogenatablehydrocarbons, it is ordinarily a preferred practice to include an alkalior alkaline earth metal component in the composite. More precisely, thisoptional component is selected from the group consisting of thecompounds of the alkali metals-cesium, rubidium, potassium, sodium, andlithium-and the compounds of the alkaline earth metals-calcium,strontium,

barium and magnesium. Generally, good results are obtained in theseembodiments when this component constitutes about 1 to about 5 wt.percent of the composite, calculated on an elemental basis. Thisoptional alkali or alkaline earth metal component can be incorporated inthe composite in any of the known ways, with impregnation with anaqueous solution of a suitable water-soluble, decomposable compoundbeing preferred.

An optional ingredient for the tetrametallic catalyst of the presentinvention is a Friedel-Crafts metal halide component. This ingredient isparticularly useful in hydrocarbon conversion embodiments of the presentinvention wherein it is preferred that the catalyst utilized has astrong acid or cracking function associated therewithfor example, anembodiment wherein hydrocarbons are to be hydrocracked or isomerizedwith the catalyst of the present invention. Suitable metal halides ofthe Friedel- Crafts type include aluminum chloride, aluminum bromide,ferric chloride, ferric bromide, zinc chloride and the like compounds,with the aluminum halides and particularly aluminum chloride ordinarilyyielding best results. Generally, this optional ingredient can beincorporated into the composite of the present invention by any of theconventional methods for adding metallic halides of this type; however,best results are ordinarily obtained when the metallic halide issublimed onto the surface of the carrier material according to thepreferred method disclosed in US. Pat. No. 2,999,074. The component cangenerally be utilized in any amount which as catalytically effective,with a value selected from the range of about 1 to about 100 wt. percentof the carrier material generally being preferred.

Regardless of the details of how the components of the catalyst arecombined with the porous carrier material, the final catalyst generallywill be dried at a temperature of about 200 to about 600 F. for a periodof at least about 2 to about 24 hours or more, and finally calcined oroxidized at a temperature of about 700 F. to about 1100 F. in an airatmosphere for a period of about 0.5 to about hours in order to convertsubstantially all of the metallic components substantially to the oxideform. In the case where a halogen component is utilized in the catalyst,best results are generally obtained when the halogen content of thecatalyst is adjusted during the calcination step by including a halogenor a halogen-containing compound in the air atmosphere utilized. Inparticular, when the halogen component of the catalyst is chlorine, itis preferred to use a mole ratio of H 0 to HCl of about 20:1 to about100:1 during at least a portion of the calcination step in order toadjust the final chlorine content of the catalyst to a range of about0.5 to about 1.5 wt. percent.

It is an essential feature of the present invention that the resultantoxidized catalytic composite is subjected to a substantially water-freereduction step prior to its use in the conversion of hydrocarbons. Thisstep is designed to selectively reduce the platinum or palladium,iridium and rhenium components to the corresponding metals and to insurea uniform and finely divided dispersion of these metallic componentsthroughout the carrier material, while maintaining the tin component ina positive oxidation state. Preferably, substantially pure and dryhydrogen (i.e. less than 20 vol. p.p.m. H O) is used as the reducingagent in this step. The reducing agent is contacted with the oxidizedcatalyst at conditions including a temperature of about 800 F. to about1200 F. and a period of time of about 0.5 to 2 hours elfective to reducesubstantially all of the platinum or palladium, iridium and rheniumcomponents to their elemental metallic state while maintaining the tincomponent in an oxidation state above that of the elemental metal. Thisreduction treatment may be performed in situ as part of a start-upsequence if precautions are taken to predry the plant to a substantiallywaterfree state and if substantially water-free hydrogen is used. Theresulting reduced catalytic composite may, in some cases, bebeneficially subjected to a presulfiding operation designed toincorporate in the catalytic composite from about 0.05 to about 0.5 wt.percent sulfur calculated on an elemental basis. Preferably, thispresulfiding treatment takes place in the presence of hydrogen and asuitable sulfur-containing compound such as hydrogen sulfide, lowermolecular weight mercaptans, organic sulfides, etc. Typically, thisprocedure comprises treating the selectively reduced catalyst with asulfiding gas such as a mixture of hydrogen and hydrogen sulfide havingabout 10 moles of hydrogen per mole of hydrogen sulfide at conditionssuflicient to effect the desired incorporation of sulfur, generallyincluding a temperature ranging from about 50 F. up to about 1100 F. ormore. It is generally a good practice to perform this presulfiding stepunder substantially water-free conditions.

According to the present invention, a hydrocarbon charge stock andhydrogen are contacted with a tetrametallic catalyst of the typedescribed above in a hydrocarbon conversion zone. This contacting may beaccomplished by using the catalyst in a fixed bed system, a moving bedsystem, a fluidized bed system, or in a batch type operation; however,in view of the danger of attrition losses of the valuable catalyst andof well known operational advantages, it is preferred to use a fixed bedsystem. In this system, a hydrogen-rich gas and the charge stock arepreheated by any suitable heating means to the desired reactiontemperature and then are passed, into a conversion zone containing afixed bed of the catalyst type previously characterized. It is, ofcourse, understood that the conversion zone may be one or more separatereactors with suitable means therebetween to insure that the desiredconversion temperature is maintained at the entrance to each reactor. Itis also important to note that the reactants may be contacted with thecatalyst bed in either upward, downward, or radial flow fashion with thelatter being preferred. In addition, the reactants may be in the liquidphase, a mixed liquid-vapor phase, or a vapor phase when they contactthe catalyst, with best results obtained in the vapor phase.

In the case where the tetrametallic catalyst of the present invention isused in a reforming operation, the reforming system will comprise areforming zone containing a fixed bed of the catalyst type previouslycharacterized. This reforming zone may be one or more separate reactorswith suitable heating means therebetween to compensate 5 the endothermicnature of the reactions that take place in each catalyst bed. Thehydrocarbon feed stream that is charged to this reforming system willcomprise hydrocarbon fractions containing naphthenes and paraffins thatboil within the gasoline range. The preferred charge stocks are thoseconsisting essentially of naphthenes and parafiins, although in somecases aromatics and/or olefins may also be present. This preferred classincludes straight run gasolines, natural gasolines, synthetic gasolinesand the like. On the other hand, it is frequently advantageous to chargethermally or catalytically cracked gasolines or higher boiling fractionsthereof. Mixtures of straight run and cracked gasolines can also be usedto advantage. The gasoline charge stock may be a full boiling gasolinehaving an initial boiling point of from about 50 F. to about F. and anend boiling point within the range of from about 325 F. to about 425 F.,or may be a selected fraction thereof which generally will be a higherboiling fraction commonly referred to as a heavy naphtha-for example, anaphtha boiling in the range of C to 400 F. In some cases, it is alsoadvantageous to charge pure hydrocarbons or mixtures of hydrocarbonsthat have been extracted from hydrocarbon distillates-for example,straight-chain paraflins-which are to be converted to aromatic. It ispreferred that these charge stocks be treated by conventional catalyticpretreatment methods such as hydrorefining, hydrotreating,hydrodesulfurization, etc., to remove substantially all sul- 13 furous,nitrogenous and water-yielding contaminants therefrom.

In other hydrocarbon conversion embodiments, the charge stock will be ofthe conventional type customarily used for the particular kind ofhydrocarbon conversion being effected. For example, in a typicalisomerization embodiment the charge stock can be a paraffinic stock richin C to C normal paraffins, or a normal butanerich stock, or an-hexane-rich stock, or a mixture of xylene isomers, etc. In adehydrogenation embodiment, the charge stock can be any of the knowndehydrogenatable hydrocarbons such as an aliphatic compound containing 2to 30 carbon atoms per molecule, a C to C normal paraffin, a C to Calkylaromatic, a naphthene and the like. In hydrocracking embodiments,the charge stock will be typically a gas oil, heavy cracked cycle oil,etc. In addition, alkylaromatic and naphthenes can be convenientlyisomerized by using the catalyst of the present invention. Likewise,pure hydrocarbons or substantially pure hydrocarbons can be converted tomore valuable products by using the tetrametallic catalyst of thepresent invention in any of the hydrocarbon conversion processes, knownto the art, that use a dual-function catalyst.

In a reforming embodiment, it is generally preferred to utiilze thenovel tetrametallic catalytic composite in a substantially water-freeenvironment. Essential to the achievement of this condition in thereforming zone is the control of the water level present in the chargestock and the hydrogen stream which is being charged to the zone. Bestresults are ordinarily obtained when the total amount of water enteringthe conversion zone from any source is held to a level less than 50p.p.m. and preferably less than 20 p.p.m.; expressed as weight ofequivalent water in the charge stock. In general, this can beaccomplished by careful control of the water present in the charge stockand in the hydrogen stream. The charge stock can be dried by using anysuitable drying means known to the art such as a conventional solidadsorbent having a high selectivity for water; for instance, sodium orcalcium crystalline aluminosilicates, silica gel, activated alumina,molecular sieves, anhydrous calcium sulfate, high surface area sodiumand the like adsorbents. Similarly, the water content of the chargestock may be adjusted by suitable stripping operations in afractionation column or like device. And in some cases, a combination ofadsorbent drying and distillation drying may be used advantageously toeffect almost complete removal of water from the charge stock.Preferably, the charge stock is dried to a level corresponding to lessthan 20 p.p.m. of H equivalent. In general, it is preferred to dry thehydrogen stream entering the hydrocarbon conversion zone down to a levelof about vol. p.p.m. of Water or less. This can be convenientlyaccomplished by contacting the hydrogen stream with a suitable desiccantsuch as those mentioned above.

In the reforming embodiment, an eflluent stream is withdrawn from thereforming zone and passed through a cooling means to a separation zone,typically maintained at about 25 to 150 F., wherein a hydrogen-rich gasis separated from a high octane liquid product, commonly called anunstabilized reformate. When a super-dry operation is desired, at leasta portion of this hydrogen-rich gas is withdrawn from the separatingzone and passed through an adsorption zone containing an adsorbentselective for water. The resultant substantially water-free hydrogenstream can then be recycled through suitable compressing means back tothe reforming zone. The liquid phase from the separating zone istypically withdrawn and commonly treated in a fractionating system inorder to adjust the butane concentration, thereby controlling front-endvolatility of the resulting reformate.

The conditions utilized in the numerous hydrocarbon conversionembodiments of the present invention are those customarily used in theart for the particular reaction, or combination of reactions, that is tobe effected. For instance, alkylaromatic and paraffin isomerizationconditions include: a temperature of about 32 F. to about 1000 F. andpreferably about 75 to about 600 F.; a pressure of atmospheric to aboutatmospheres; a hydrogen to hydrocarbon mole ratio of about 0.5 :1 toabout 20:1 and a LHSV (calculated on the basis of equivalent liquidvolume of the charge stock contacted with the catalyst per hour dividedby the volume of conversion zone containing catalyst) of about 0.2 hr.-to 10 hrr Dehydrogenation conditions include: a temperature of about 700to about 1250" F., a pressure of about 0.1 to about 10 atmospheres, aliquid hourly space velocity of about 1 to 40 hr. and a hydrogen tohydrocarbon mole ratio of about 1:1 to 20: 1. Likewise, typicallyhydrocracking conditions include: a pressure of about 500 p.s.i.g. toabout 3000 p.s.i.g.; a temperature of about 400 F. to about 900 F.; aLHSV of about 0.1 hr. to about 10 hr; and hydrogen circulation rates ofabout 1000 to 10,000 s.c.f. per barrel of charge.

In the reforming embodiment of the present invention the pressureutilized is selected from the range of about 0 p.s.i.g. to about 1000p.s.i.g., with the preferred pressure being about 50 p.s.i.g. to about600 p.s.i.g. Particularly good results are obtained at low pressure;namely, a pressure of about 50 to 350 p.s.i.g. In fact, it is a singularadvantage of the present invention that it allows stable operation atlower pressure than have heretofore been successfully utilized inso-called continuous reforming systems (i.e. reforming for periods ofabout 15 to about 200 or more barrels of charge per pound of catalystwithout regeneration) with all platinum monometallic catalysts. In otherwords, the catalyst of the present invention allows the operation of acontinuous reforming system to be conducted at lower pressure (i.e. 100to about 350 p.s.i.g.) for about the same or better catalyst life beforeregeneration as has been heretofore realized with conventionalmonometallic catalysts at higher pressures (i.e. 400 to 600 p.s.i.g.).On the other hand, the stability feature of the present inventionenables reforming operations conducted at pressures of 400 to 600p.s.i.g. to achieve substantially increased catalyst life beforeregeneration.

Similarly, the temperature required for reforming is generally lowerthan that required for a similar reforming operation using a highquality catalyst of the prior art. This significant and desirablefeature of the present invention is a consequence of the selectivity ofthe trimetallic catalyst of the present invention for theoctane-upgrading reactions that are preferably induced in a typicalreforming operation. Hence, the present invention requires a temperaturein the range of from about 800 F. to about 1100 F. and preferably about900 F. to about 1050 F. As is well known to those skilled in thecontinuous reforming art, the initial selection of the temperaturewithin this broad range is made primarily as a function of the desiredoctane of the product reformate considering the characteristics of thecharge stock and of the catalyst. Ordinarily, the temperature then isthereafter slowly increased during the run to compensate for theinevitable deactivation that occurs to provide a constant octaneproduct. Therefore, it is a feature of the present invention that therate at which the temperature is increased in order to maintain aconstant octane product, is substantially lower for the catalyst of thepresent invention than for a high quality reforming catalyst which ismanufactured in exactly the same manner as the catalyst of the presentinvention except for the inclusion of the iridium, tin and rheniumcomponents. Moreover, for the catalyst of the present invention, the Cyield loss for a given temperature increase is substantailly lower thanfor a high quality reforming catalyst of the prior art. In addition,hydrogen production is substantially higher.

The reforming embodiment of the present invention also typicallyutilizes suflicient hydrogen to provide an amount of about 1 to aboutmoles of hydrogen per mole of hydrocarbon entering the reforming zone,with excellent results being obtained when about 5 to about 10 moles ofhydrogen are used per mole of hydrocarbon. Likewise, the liquid hourlyspace velocity (LHSV) used in reforming is selected from the range ofabout 0.1 to about 10 hrr with a value in the range of about 1 to about5 hr." being preferred. In fact, it is a feature of the presentinvention that it allows operations to be conducted at higher LHSV thannormally can be stably achieved ina continuous reforming process with ahigh quality reforming catalyst of the prior art. This last feature isof immense economic significance because it allows a continuousreforming process to operate at the same throughput level with lesscatalyst inventory than that heretofore used with conventional reformingcatalysts at no sacrifice in catalyst life before regeneration.

The following working examples are given to illustrate further thepreparation of the tetrametallie catalytic composite of the presentinvention and the use thereof in the conversion of hydrocarbons. It isunderstood that the examples are intended to be illustrative rather thanrestrictive.

EXAMPLE I This example demonstrates a particularly good method ofpreparing the prefered catalytic composite of the present invention.

An alumina carrier material compirsing 1 inch spheres is prepared by:forming an aluminum hydroxyl chloride sol by dissolving substantiallypure aluminum pellets in a hydrochloric acid solution, addinghexamethylenetetramine to the resulting sol, gelling the resultingsolution by dropping it into an oil bath to form spherical particles ofan aluminum hydrogel, aging and washing the resulting particles andfinally drying and calcining the aged and washed particles to formspherical particles of gamma-alumina containing about 0.3 wt. percentcombined chloride. Additional details as to this method of preparing thepreferred carrier material are given in the teachings of US. Pat. No.2,620,314.

An aqueous solution containing chloroplatinic acid, chloroiridic acid,perrhenic acid, stannic chloride, and hydrogen chloride is then used toimpregnate the gammaalumina particles in amounts, respectively,calculated to result in a final composite containing, on an elementalbasis, 0.375 Wt. percent platinum, 0.375 wt. percent iridium, 0.375 wt.percent rhenium and 0.5 wt. percent tin. In order to insure uniformdistribution of the metallic components throughout the carrier material,the amount of hydrogen chloride corresponds to about 10 wt. percent ofthe alumina particles. This impregnation step is performed by adding thecarrier material particles to the impregnation mixture with constantagitation. In addition, the volume of the solution is two times thevolume of the carrier material particles. The impregnation mixture ismaintained in contact with the carrier material particles for a periodof about /2 hour at a temperature of about 70 F. Thereafter, thetemperature of the impregnation mixture is raised to about 225 F. andthe excess solution is evaporated in a period of about 1 hour. Theresulting dried particles are then subjected to a calcination treatmentin an air atmosphere at a temperature of about 925 F. for about 1 hour.The calcined spheres are then contacted with an air stream containing H0 and HCl in a mole ratio of about 40:1 for about 4 hours at 975 F. inorder to adjust the halogen content of the catalyst particles to a valueof about 0.90.

The resulting catalyst particles are analyzed and found to contain, onan elemental basis, about 0.375 wt. percent platinum, about 0.375 wt.percent rhenium, about 0.375 wt. percent iridinum, about 0.5 wt. percenttin and about 0.85 wt. percent chloride. For this catalyst, the atomicratio of tin to platinum is 2.211, the atomic ratio of 16 iridium toplatinum is 1.02:1, and the atomic ratio of rhenium to platinum is1.05:1.

Thereafter, the catalyst particles are subjected to a dry pre-reductiontreatment designed to reduce the platinum, iridium and rheniumcomponents to the elemental state while maintaining the tin component ina positive oxidation state by contacting them for 1 hour with asubstantially pure hydrogen stream containing less than 5 vol. ppm. H Oat a temperature of about 1050 F., a pressure slightly above atmosphericand a flow rate of the hydrogen stream through the catalyst particlescorresponding to a gas hourly space velocity of about 720 hrr EXAMPLE IIA portion of the spherical tetrametallic catalyst particles produced bythe method described in Example I are loaded into a scale model of acontinuous, fixed bed reforming plant of conventional design. In thisplant a heavy Kuwait naphtha and hydrogen are continuously contacted atreforming conditions: a liquid hourly space velocity of 1.5 hr.- apressure of p.s.i.g., a hydrogen to hydrocarbon mole ratio of 8.1, and atemperature sufiicient to continuously produce a C reformate of 102 F1clear. It is to be noted that these are exceptionally I severeconditions.

The heavy Kuwait naphtha has an API gravity at 60 F. of 60.4, an initialboiling point of 184 F., a 50% boiling point of 256 F., and an endboiling point of 360 F. In addition, it contains about 8 vol. percentaromatics, 71 vol. percent parafiins, 21 vol. percent naphthenes, 0.5wt. percent parts per million sulfur, and 5 to 8 wt. parts per millionwater. The F-l clear octane number of the raw stock is 40.0.

The fixed bed reforming plant is made up of a reactor containing thetetrametallic catalyst, a hydrogen separation zone, a debutanizercolumn, and suitable heating, pumping, cooling and controlling means. Inthis plant, a hydrogen recycle stream and the charge stock arecommingled and heated to the desired temperature. The resultant mixtureis then passed downfiow into a reactor containing the tetrametalliccatalyst as a fixed bed. An efiiuent stream is then withdrawn from thebottom of the reactor, cooled to about 55 F. and passed to a separatingzone wherein a hydrogen-rich gaseous phase separates from a liquidhydrocarbon phase. A portion of the gaseous phase is continuously passedthrough a high surface area sodium scrubber and the resulting water-freehydrogen stream recycled to the reactor in order to supply hydrogenthereto, and the excess hydrogen over that needed for plant pressure isrecovered as excess separator gas. The liquid hydrocarbon phase from thehydrogen separating zone is withdrawn therefrom and passed to adebutanizer column of conventional design wherein light ends are takenoverhead as debutanizer gas and a C reformate stream recovered asbottoms.

The test run is continued for a catalyst life of about 20 barrels ofcharge per pound of catalyst utilized, and it is determined that theactivity, selectivity, and stability of the present tetrametalliccatalyst are vastly superior to those observed in a similar type testwith a conventional commercial reforming catalyst. More specifically,the results obtained from the subject catalyst are superior to theplatinum metal-containing catalyst of the prior art in the areas ofhydrogen production, (3 yield at octane, average rate of temperatureincrease necessary to maintain octane, and 0 yield decline rate.

It is intended to cover by the following claims all changes andmodifications of the above disclosure of the present invention whichwould be self-evident to a man of ordinary skill in the catalystformulation art or the hydrocarbon conversion art.

I claim as my invention:

1. A catalytic composite comprising a combination of a platinum orpalladium component, an iridium component, a rhenium component and a tincomponent with a porous carrier material in amounts sufficient to resultin a composite containing, on an elemental basis, about 0.01 to about 2wt. percent platinum or palladium, about 0.01 to about 2 wt. percentiridium, about 0.01 to about 2 wt. percent rhenium and about 0.01 toabout wt. percent tin, wherein substantially all of the platinum orpalladium component, the iridium component and the rhenium component arepresent in the elemental metallic state and wherein substantially all ofthe tin component is present in an oxidation state above that of theelemental metal.

2. A catalytic composite as defined in claim 1 wherein the platinum orpalladium component is platinum metal.

3. A catalytic composite as defined in claim 1 wherein the tin componentis tin oxide.

4. A catalytic composite as defined in claim 1 wherein the platinum orpalladium component is palladium metal.

5. A catalytic composite as defined in claim 1 wherein the porouscarrier material is a refractory inorganic oxide.

6. A catalytic composite as defined in claim 5 wherein the refractoryinorganic oxide is gammaor eta-alumina.

7. A catalytic composite comprising a combination of a catalyticcomposite defined in claim 1 with a halogen component in an amountsufiicient to result in a composite, containing on an elemental basis,about 0.1 to about 3.5 wt. percent halogen.

8. A catalytic composite as defined in claim 7 wherein the halogencomponent is chlorine or a compound of chlorine.

9. A catalytic composite as defined in claim 1 wherein the compositecontains, on an elemental basis, about 0.05 to about 1 wt. percentplatinum or palladium metal, about 0.05 to about 1 wt. percent iridium,about 0.05 to about 1 wt. percent rhenium and about 0.05 to about 2 wt.percent tin.

10. A catalytic composite as defined in claim 1 wherein the atomic ratioof tin to the platinum or palladium metal is about 0.1:1 to about 3:1,wherein the atomic ratio of rhenium to the platinum or palladium metalis about 0.1:1 to about 3:1 and wherein the atomic ratio of iridium toplatinum or palladium is about 0.1:1 to about 2:1.

11. A catalytic composite comprising a combination of a platinumcomponent, an iridium component, a rhenium component, a tin component,and a halogen component with an alumina carrier material in amountssufiicient to result in a composite containing, on an elemental basis,about 0.01 to 2 wt. percent platinum, about 0.01 to about 2 wt. percentiridium, about 0.01 to 2 wt. percent rhenium, about 0.01 to about 5 wt.percent tin and about 0.1 to about 3.5 wt. percent halogen, wherein thetin component is uniformly distributed throughout the carrier material,wherein substantially all of the platinum, iridium and rheniumcomponents are present in the elemental metallic state and whereinsubstantially all of the tin component is present in an oxidation stateabove that of the elemental metal.

12. A catalytic composite as defined in claim 11 wherein the halogencomponent is a chlorine or a compound of chlorine.

13. A catalytic composite comprising a combination of the catalyticcomposite defined in claim 11 with a sulfur component in an amountsuflicient to result in a composite containing about 0.05 to about 0.5wt. percent sulfur.

14. A catalytic composite as defined in claim 11 wherein the atomicratio of tin to platinum is about 0.1 :1 to about 3: 1, wherein theatomic ratio rhenium to platinum is about 0.1:1 to about 3:1 and whereinthe atomic ratio of iridium to platinum is about 0.1:1 to about 2:1.

15. A catalytic composite as defined in claim 11 wherein the compositecontains, on an elemental basis, about 0.05 to about 1 wt. percentplatinum, about 0.05 to about 1 wt. percent iridium, about 0.05 to about1 wt. percent rhenium, about 0.05 to about 2 wt. percent tin and about0.5 to about 1.5 wt. percent halogen.

16. A process for converting a hydrocarbon which comprises contactingthe hydrocarbon and hydrogen with the catalytic composite contained inclaim 1 at hydrocarbon conversion conditions.

17. A process for reforming a gasoline fraction which comprisescontacting the gasoline fraction and hydrogen with the catalyticcomposite defined in claim 1 at reforming conditions.

18. A process as defined in claim 17 wherein said reforming conditionsinclude a temperature of about 800 to about 1100 F., a pressure of about0 to about 1000 p.s.i.g., a liquid hourly space velocity of about 0.1 toabout 10 hrf and a mole ratio of hydrogen to hydrocarbon of about 1:1 toabout 20:1.

19. A process as defined in claim 17 wherein the pressure is about 50 toabout 350 p.s.i.g.

20. A process as defined in claim 17 wherein the con tacting isperformed in a substantially water-free environment.

21. A process for reforming a gasoline fraction which comprisescontacting the gasoline fraction and hydrogen with the catalyticcomposite defined in claim 11 at reforming conditions.

22. A process for reforming -a gasoline fraction which comprisescontacting the gasoline fraction and hydrogen with the catalyticcomposite defined in claim 15 at reforming conditions.

23. A process as defined in claim 22 wherein the reforming conditionsinclude a pressure of about 50 to about 350 p.s.i.g.

References Cited UNITED STATES PATENTS 2,861,959 11/1958 Thorn et a1.208138 2,952,611 9/1960 Haxton et al. 208 3,415,737 12/ 1968 Kluksdahl208-138 3,449,237 6/1969 Jacobson et al. 208-138 3,578,583 5/1971 Buss208138 3,578,584 5/1971 Hayes 252466 PT 3,631,215 12/ 1971 Clippinger etal 208138 DELBERT E. GANTZ, Primary Examiner S. L. BERGER, AssistantExaminer US. Cl. X.R.

208l12, 138; 252-441, 466 PT; 260-668, 683.3, 683.68

